2-(((1-Adamantylcarbonyl)oxy)methyl)-6-imino-2,3,3a,9a-tetrahydro-6H-furo[2',3':4,5][1,3]oxazolo[3,2-a]pyrimidin-3-yl 1-adamantanecarboxylate 64130-39-8 AIDS-128833 AIDS128833 NSC300279